Tool



' July so 1946. H. E. 'DICKERMAN TOOL Fil d Dec; 27, 1944 I INVENTOR'. 1 MilM/ww.

Eatente d July 30, 1946 UNITED STATES PATENT OFFICE TOOL Hubert E. Dickerman, Springfield, Mass.

Application December 27, 1944, Serial No. 569,956

3 Claims. 1

This invention relates .to tools and is directed more particularly to apparatus for punching operations and the like.

The principal objects of the invention are directed to apparatus for punching operations and the like which is characterized by novel features that increase life of the tool, decrease power consumption, obviate galling and seizing of punch and die and reduce shut-down time in general.

According to prior practice galling and seizing of a punch and die is a frequent difficulty due to improper relative dimensions of the punch and die which results in improper break and the slugs punched out from a piece of metal tend to jump upwardly and outwardly from the die if proper relative dimensions are used. This frequently causes great damage to the apparatus due to the slugs becoming caught therein.

According to this invention, the punch and die are relatively proportioned to provide a correct break as the slug is punched from the stock thereby to obviate galling and seizing of the punch and die while by reason of the novel form of the punch and die the blank punched is prevented from jumping upwardly and outwardly from the die.

With the foregoing and various other novel features and advantages and other objects of my invention as will become more apparent as the description proceeds, the invention consists in certain novel features of construction and in the combination and arrangement of parts as will be hereinafter more particularly pointed out in the claims hereunto annexed and more fully described and referred to in connection with the accompanying drawing wherein the single figure is a sectional elevational view through a die showing a piece of stock thereon and a punch for cooperating with the die for punching a hole in the stock.

Referring now to the drawing in detail. the invention will be more fully described. In describing the invention reference will be made to a piece of stock, ordinary steel, in which it is desired to punch a round hole. For illustrative purposes, it will be assumed that the stock is in thickness and that the hole to be punched therein will be V3" in diameter.

A die is represented by 2 which, as shown, has

a hole for a punch 4. A piece of metal is represented by 6 which is placed between the punch and die. It will be understood that the punch and die are suitably associated with relatively movable members of press apparatus whereby the punch is forced through the piece 6. As an example, where the hole in the metal member 6 is to be V in diameter the finished hole must be .125 minus .001" and plus .001".

To produce such a punched hole, the diameter 0 of the punch will be .1263 minus .0007" and plus .0002". The entrance diameter 10 ofthe hole in the die will be about 10% greater than the diameter of the punch or .1388 minus .001" and plus .000.

The depth of the hole in the die or thickness of the die will be great enough to allow for a restricted throat or diameter therein which is disposed downwardly from the entrance thereof a distance l2 that is greater than the thickness of the stock and preferably which is equal to about one and one-half times the thickness of the stock.

The diameter I4 of the restriction or throat will be slightly greater than the diameter of the punch and slightly smaller than the top of the hole preferably .1368 minus .0005" and plus .000". The dimensions given will not only provide the desired break for the stock but will provide a hole in the die having an upper part that converges downwardly from its entrance to the restriction or throat as shown.

The dimension it of the die from the restriction downwardly may vary and if desired the die may be formed from cooperating upper and lower parts having adjacent faces in contiguous relation on a plane represented by a dash-dot line passing through the restricted part of the hole in the die. The sides of the lower portion of the hole in the die converge downwardly from the restriction at an angle l8 from A1 to of a degree on each side.

In operation, as the punch is moved downwardly to engage the stock and punch a plug downwardly into and through the hole in the die, the break and the relative dimensions are such that seizing and galling are eliminated while the punched slug is pushed downwardly in the hole in the die past or into the restriction thereof. As the punch is moved upwardly relative to the die, the slug is prevented from jumping upwardly or being drawn upwardly out of the hole in the die by adhering to the end of the punch.

The dimensions given not only produce a correct break so as to provide a clean hole in the stock but the difficulties caused by galling and seizing are obviated thereby increasing useful tool life and. decreasing the power requirements.

The example given is in connection with ordinary steel stock, say 1020 S. A. E., but the features of the invention may be adapted to other grades asse and thickness of metal by changes and modifications which may be made within the scope of the invention.

While in the form of the invention described, dimension ID of the entrance to the hole is about 10 percent greater than the diameter 8 of the punch the percentage may vary according to stock and diameter of hole to be punched from to 13%.

The invention may be embodied in other specific forms without departin from the essential characteristics thereof. Hence, the present embodiments are therefore to be considered in all respects merely as being illustrative and not as being restrictive, the scope of theinvention being indicated by the appended claims rather than by the foregoing description, and all modifications andvariations as fall within the meaning and the diameter of the restricted portionoi the ht; 7 being from 5 to 13% greater than the diameter 7 the punch.

2. A punching construction comprising in combination, a punch and a die having a punch receiving hole therein, said hole having a restricted portion disposed downwardly from the entrance thereof, and the side walls of the hole diverging in opposite directions from said restricted portion, the diameter of the restricted portion of the hole being 10% greater than the diameter of the punch.

' 3. A punch and die construction comprising in combination, a punch of a certain dianieter, a die having a punch receiving hole therethrough, the upper entrance of said hole being from 5 to 13% greater in diameter than said certain diameter with the sides of the hole converging downwardly from said upper entrance of the hole to form a restricted portion of the hole intermediate the ends of the hole which is slightly greater in diameter than said certain diameter and. the sides of the hole diverging downwardly from said restricted portion to the lower portion of said hole at an angle of one-quarter to three-quarters of a degree on a side relative to the longitudinal axi of said hole. I

HUBERT E. DICKERMAN. 

